Saw chain
A saw chain is a component of a chain saw or chain milling machine designed as an endless chain with special cutting links , which removes material from the material to be processed.
execution
Nowadays so-called toothed tooth chains are used almost exclusively in chainsaws.
The individual links of the chain (drive link, connecting link, cutting link) are then firmly riveted together, cutting link on the left, connecting link, drive link, connecting link, cutting link on the right and drive link.
Functions of the individual links:
- The drive link transfers the drive force from the pinion (also called drive star here) to the chain and ensures that the adhesive chain oil is distributed on the rail through the driver . These drivers are designed to be triangular towards the inside of the chain. The outside is mostly smooth. However, there are also chains whose drive links have specially shaped sliding plates on the top, which ensure a smoother cut.
- The connecting link connects drive and cutting links.
- The cutting link is responsible for chipping the wood. It's smooth on the bottom. A right-angled cutting edge with a leading spacer nose (depth limiter) is formed on the top. The top of the tooth (leading) lifts the wood fiber, the tooth side cuts the fiber. The chip thickness is determined by the vertical distance between the depth limiter and the upper edge of the cutting tooth. This distance should be filed down to the correct size with a depth gauge and a flat file. Some chains require a 0.64 mm (0.025 ") gauge; others require 0.56 mm (0.22"). If you file the depth limiter too deep, the chip thickness increases, but the power of the chain saw is overwhelmed and the risk of kickback increases. When it comes to teeth, a distinction is made between half chisels and full chisels. Half chisels with rounded side edges are universally usable chains that forgive even minor errors when sharpening, whereas full chisels with around 20% higher cutting performance are mostly used for medium to large saws in the commercial sector for felling and cutting clean wood, as these are due to the sensitive point shape of the cutting tooth blunt faster with dirty wood and foreign body contact and require a lot of experience or suitable tools for sharpening. Half chisels have a lower kickback effect due to the lower material removal. The shape of the cutting link is decisive for the cutting behavior.
The angles on the cutting links are very important for the work result and operational safety. The following angles are usually specified explicitly in the documents for each chain saw and also in the documents for each saw chain: side plate file angle or sharpening angle (80 - 85 - 90 °), tooth roof angle or roof cutting angle (30 - 35 °), face angle (none Specification) and file guide angle (90 °). Typical example values are shown in brackets. This information is important because the saw chain is usually filed several times by the user, i.e. sharpened and freed from damage from operation, which is not trivial due to the different angles in several dimensions. The industry therefore offers various sharpening aids, e.g. B. in the form of gauges, which are attached magnetically under the file and show the user an optical template.
Saw chains are manufactured in a wide variety of variations. When buying a saw chain, the chain pitch, width and length must be taken into account, the dimensions of which must be observed.
- The chain pitch (given in inches) is the distance between the rivet bolts (in the connecting link) measured from center to center. To determine the pitch, the distance between 3 rivets following one another must be measured, then divide by 2 = chain pitch. 1/4 ", 3/8" (or 0.375 "), 3 / 8H, 0.325" and 0.404 "are offered.
- The dimension of the chain width corresponds to the strength of the drive link = the groove width in the rail. 1.1 mm, 1.3 mm, 1.5 mm and 1.6 mm as well as 2.0 mm are available as .404 " harvester chains .
In the field of woodworking machines, there are sometimes even larger pitches than the .404.
- The chain length is sometimes given in cm, but the number of drive links (e.g. 52 E for endless chain or 52 Tg for 52 drive links) is also common.
A complete purchase information would therefore be z. B. 3/8 "- 1.3 - 52E.
Historical chains
Risserzahn 2-link chain or rider chain
In 1934 Alfonso Lange, Altona-Hochkamp, applied for a patent for this chain for DOLMAR at the Reich Patent Office. It consisted of 2 changing chain links (Risserzahn), which were guided on a central web of the guide rail. The sheet metal tabs pulled down below the rivets act as side stops (guides) on the left and right. It was used in the Dolmar saws C, CL in a thickness of 5 mm, in the CK, CP and CF in a thickness of 3 mm. This chain consists of 4 different link types: left cutting link (LS), right cutting link (RS), left reamer (LR), right reamer (RR). The arrangement as an endless chain was as follows: LS, RS, LS, RS, LS, RS, LR, RR, followed by the repetition. The only task of the cutting links is to cut through the wood fiber. The sawdust is removed by the scrapers. So-called rider chain, the horse symbolizes the guide rail, the rider with his two legs as side guides the chain link, the chain "rides" on the rail.
AKCO chain
This chain was used on the saws B60, D60, N60 by A. Kühn Coswig / Dresden in the GDR. It is a 3-link ripped tooth chain. The chain pitch is 15 × 15 with a 2 mm drive link thickness. In addition to the right and left cutting links, the outer part of the drive link is used as a clearing link.
Mafell chain
This chain looks very similar to today's modern chopper tooth chain, but is still a ripper tooth chain with 3 plates (right and left incisors and drive links). There is also a scraper in front of the cutting edges so that this chain has 3 scrapers (half left, center and half right). This scraper is used as a depth limiter on today's tooth chains. It was used in the US50 carpenter's cross-cut chain saw from Mafell .
variants
Saw chains are used:
- with chainsaws for manual wood harvesting and tree care , as a joinery saw in carpentry , and also in sculpture
- as a tool for wood harvesters for mechanical wood harvesting
- as a cutting tool (chop saw) in sawmills
- for chain cutters (chain milling machines)
- with the hand chain saw (saw chain with two handles)
- as a cutting and milling tool in woodworking centers ( automatic processing machines )
- in stone processing or quarries , to saw large blocks out of the rock or to cut blocks into smaller ones
- when renovating buildings ( horizontal barrier )
Special forms
Carbide chain
Such chains are used by saw manufacturers in rescue saws and can cut stones such as aerated concrete, clinker, sandstone, plaster of paris and soft sheet metal, as the cutting link has teeth that are coated with carbide. They are mainly used by the fire brigade and the THW , but are also used for wood that is frozen or heavily soiled by earth, stones or metal parts (nails etc.), such as used timber or old roof trusses. As a competing product, there is a toothed chain with a chrome layer three times thicker than usual. On the other hand, tests with cobalt alloys have not reached the market. As with the hard metal version, the re-sharpening problem occurs here; only diamond or silicon carbide are suitable for this .
Special chain
This type of chain was used on small American chainsaws ( McCulloch , Poulan) and on the Dolmar 101 Super. It has a different cutting tooth with a steeply sloping roof and is sharpened directly in the chainsaw without dismantling using a manually operated sanding block that is permanently installed on the saw or by attaching a plastic part with an integrated semicircular whetstone to the tip of the sword when the chain is (high) running.
Stone saw chain
This saw chain consists of double cone cutting bodies, each connected with a steel cable. At the thickest point of the cutting body is the cutting material, such as. B. diamond incorporated. Individual cutting bodies can be screwed apart. This allows the saw chain to be shortened or lengthened as required.
The chain is threaded around the block to be sawed or through a hole. A drive wheel sets the chain in motion. The direction of pull determines the course of the cut. During the sawing process, the cut is cooled with water and the stone removed is rinsed out of the cut. The chain must be continuously retensioned during the cut.
Web links
swell
- ↑ Package insert for the HITACHI saw chain 781124 with the dimensions 3/8 "LP; 1.3 mm; 52
- ↑ Brochure "STIHL Sharpening Saw Chains 2012-10"
- ↑ Package insert for the HITACHI saw chain 781124 with the dimensions 3/8 "LP; 1.3 mm; 52 and operating instructions for the HITACHI chainsaw CS33EB, which uses such a chain